A high incidence of intussusception in Japan as studied in a sentinel hospital over a 25-year period (1978-2002)

Characteristics of intussusception among children in Hokkaido, Japan, during the pre- and post-rotavirus vaccine eras (2007-2016)

AIM

To analyse the epidemiology of intussusception in Hokkaido Prefecture, Japan during a 10-year period spanning the introduction of the rotavirus (RV) vaccine (2007-2016).

METHODS

Using a standard questionnaire, a retrospective surveillance was conducted across 17 hospitals with paediatric beds in Hokkaido Prefecture. We compared the data between the pre-vaccine era (2007-2011) and post-vaccine era (2012-2016).

RESULTS

In total, 208 and 110 intussusception cases were in the pre- and post-vaccine eras, respectively. A significant reduction of the intussusception incidence in children aged <1 year was observed from the pre- to the post-vaccine era (102.4-56.5 per 100 000 infants; incidence rate ratio, 0.55; p = 0.004). There was a relatively high-positive RV antigen detection rate (29.4%, 5/17) during the RV epidemic period in Japan (March-May) in the pre-vaccine era. None of the intussusception cases in the 31 patients with a history of RV vaccination occurred within 1 month after the administration of an RV vaccine dose.

CONCLUSIONS

The incidence of intussusception in children aged <1 year decreased significantly after RV vaccine introduction in Japan. Another survey is needed to determine how the incidence of intussusception has changed further since the introduction of routine RV vaccination in 2020.

Intussusception in children aged under two years in India: Retrospective surveillance at nineteen tertiary care hospitals

Objective

Intussusception has been linked with rotavirus vaccine (RVV) as a rare adverse reaction. In view of limited background data on intussusception in India and in preparation for RVV introduction, a surveillance network was established to document the epidemiology of intussusception cases in Indian children.

Methods

Intussusception in children 2–23 months were documented at 19 nationally representative sentinel hospitals through a retrospective surveillance for 69 months (July 2010 to March 2016). For each case clinical, hospital course, treatment and outcome data were collected.

Results

Among the 1588 intussusception cases, 54.5% were from South India and 66.3% were boys. The median age was 8 months (IQR 6, 12) with 34.6% aged 2–6 months. Seasonal variation with higher cases were documented during March-June period. The most common symptoms and signs were vomiting (63.4%), bloody stool (49.1%), abdominal pain (46.9%) and excessive crying (42.8%). The classical triad (vomiting, abdominal pain, and blood in stools) was observed in 25.6% cases. 96.4% cases were diagnosed by ultrasound with ileocolic location as the commonest (85.3%). Management was done by reduction (50.8%) and surgery (41.1%) and only 1% of the patients’ died. 91.1% cases met Brighton criteria level 1 and 3.3% Level 2. Between 2010 and 2015, the case load and case ratio increased across all regions.

Conclusion

Intussusception cases have occurred in children across all parts of the country, with low case fatality in the settings studied. The progressive rise cases could indicate an increasing awareness and availability of diagnostic facilities.

Incidence and epidemiology of intussusception among children under 2 years of age in Chenzhou and Kaifeng, China, 2009-2013

INTRODUCTION

In China, rotavirus is the leading cause of diarrhea hospitalizations among children aged <5 years. A locally manufactured rotavirus vaccine is available for private market use, but little is known about its coverage. Given the impending availability of newer rotavirus vaccines, we evaluated intussusception rates among children aged <2 years to better understand intussusception epidemiology for future vaccine safety monitoring.

METHODS

We conducted a retrospective review at 4 hospitals in Chenzhou City of Hunan Province and Kaifeng City of Henan Province. We identified intussusception cases admitted during 2009-2013 by reviewing medical records with the ICD-10 discharge code for intussusception and extracting demographic and clinical information from the electronic clinical record systems.

RESULTS

During 2009-2013, 1715 intussusception hospitalizations among 1,487,215 children aged <2 years occurred in both cities. The average annual intussusception hospitalization incidence was 112.9 per 100,000 children aged <2 years (181.8 per 100,000 children <1 year; 56 per 100,000 children 1 to <2 years). Intussusception incidence was low among infants aged <3 months and peaked at age 6-8 months. No clear seasonality was observed. Ultrasound was used to diagnose 95.9% of cases. Enema reduction was performed in 80% cases; 25% of cases in Chenzhou and 16% in Kaifeng required surgical intervention. No deaths were reported. The median time between symptom onset and admission was 1 day.

CONCLUSIONS

This study provides information on intussusception incidence and epidemiology in two cities of China during 2009-2013. Monitoring intussusception rates in this population will be important in the post-rotavirus vaccine era.

Intussusception-related Hospitalizations Among Infants Before and After Private Market Licensure of Rotavirus Vaccines in Taiwan, 2001-2013

INTRODUCTION

Rotavirus is a leading cause of acute gastroenteritis among Taiwanese children. Two globally licensed rotavirus vaccines recommended for inclusion in routine immunization programs that have been available for private market use in Taiwan since 2006 have been associated with a low risk of intussusception in postmarketing studies conducted in several countries. Our objective was to examine trends and characteristics of intussusception hospitalizations in Taiwan among children <12 months of age before and after rotavirus vaccine licensure to provide updated baseline and early postlicensure data.

METHODS

We extracted data on intussusception-related hospitalizations among children <12 months of age during 2001-2013 from the National Health Insurance Research Database. We examined patient demographics, clinical outcome and hospitalization trends, focusing on recommended ages for rotavirus vaccination (6-14, 15-24 and 25-34 weeks). We compared mean hospitalization rates for prevaccine licensure years 2001-2005 with those for postvaccine licensure years 2007-2013 using Poisson regression analysis.

RESULTS

During 2001-2013, 1998 intussusceptions hospitalizations were recorded. The mean age of hospitalization was 33 weeks. Almost all children recovered; 3 deaths occurred. The overall intussusception hospitalization rate was 75.1 per 100,000; seasonality was not evident. Hospitalization rates were greatest in children ≥25 weeks of age and occurred more frequently in boys. Prevaccine and postvaccine licensure trends in annual hospitalization rates did not significantly differ. However, mean hospitalization rates were lower during the postvaccine licensure period for children <12 months of age (rate ratio: 0.84, 95% confidence interval: 0.76-0.92) with the greatest decline among children 25-34 weeks of age (rate ratio: 0.66, 95% confidence interval: 0.55-0.78).

CONCLUSIONS

Infant intussusception in Taiwan occurs at a rate within the range of other Asian countries is rare among children <3 months of age, has a male predominance and does not have a clear seasonality pattern. We did not observe a postlicensure increase in intussusception hospitalization rates in children 6-14 weeks of age.

Intussusception among children less than 2years of age: Findings from pre-vaccine introduction surveillance in Pakistan

BACKGROUND

Rotavirus vaccination introduction in routine immunization is under consideration in Pakistan. Data on the baseline epidemiology of intussusception will inform surveillance strategies for intussusception after rotavirus vaccine introduction in Pakistan. We describe the epidemiology of intussusception-associated hospitalizations among children <2years of age in Karachi, Pakistan.

METHODS

We conducted a retrospective chart review for July 01, 2012 through June 30, 2015 at the National Institute of Child Health (NICH) and Aga Khan University Hospital (AKUH) Karachi. At AKUH, the International Classification of Disease, ninth revision, code 560.0 for intussusception was used to retrieve intussusception case records. At NICH, daily Operation Theater, Emergency Room, and surgical daycare log sheets and surgical ward census sheets were used to identify cases. Records of children who fulfilled eligibility criteria and the Brighton Collaboration level one case definition of intussusception were selected for data analysis. We used structured case report forms to extract data for the descriptive analysis.

RESULTS

We identified 158 cases of confirmed intussusception; 30 cases (19%) were from AKUH. More than half (53%) of the cases occurred in children aged 6-12months, followed by 35% among those aged <6months. Two-thirds (106/158) of the cases were male. The most common presenting complaints were vomiting and bloody stool. At NICH, almost all (93%) were managed surgically, while at AKUH, ∼57% of the cases were managed with enemas. Three deaths occurred, all from NICH. Cases occurred without any seasonality. At NICH, 4% (128/3618) of surgical admissions among children aged <2years were attributed to intussusception, while that for AKUH was 2% (30/1702).

CONCLUSION

In this chart review, intussusception predominantly affected children 0-6months of age and occurred more commonly in males. This information on the baseline epidemiology of intussusception will inform post-vaccine introduction adverse event monitoring related to intussusception in Pakistan.

Assessing the risk of intussusception and rotavirus vaccine safety in Canada

BACKGROUND

Intussusception has been identified as a rare adverse event following rotavirus immunization. We sought to determine the incidence of intussusception among infants in Canada both before and after introduction of rotavirus immunization programs.

METHODS

We used Canadian Institute for Health Information (CIHI) Discharge Abstract Database (DAD) to identify infants under 1 y of age who were admitted to a Canadian hospital, which the exception of Quebec, which does not submit data to CIHI, with a diagnosis of intussusception (ICD-10 code K56.1, and ICD-9 code 560) between January 1st, 2003 and December 31, 2013. We compared rates of intussusception hospitalization before and after rotavirus vaccine program introduction. Rates were adjusted for calendar year, age (in months), sex and region using Poisson regression models. Denominator data for infants under 1 year, stratified by age in months, were obtained from Statistics Canada.

RESULTS

Annual intussusception hospitalization rates ranged from 20-30 per 100,000 infants over the study period, with no evidence of a trend over time. Intussusception hospitalization rates were highest in infants 4 to <8 months and lowest in those under 2 months or between 10 and <12 months. Males had higher rates than females both overall and within each age group. The rate of intussusception hospitalization after rotavirus vaccine program introduction was 22.4 (95% CI: 18.3, 27.4) compared to 23.4 (95% CI: 21.5, 25.4) per 100,000 before program introduction.

CONCLUSIONS

We have described baseline intussusception hospitalization rates for infants in Canada and have found no evidence of a change in rate after implementation of routine rotavirus immunization programs.

Post-Marketing Benefit-Risk Assessment of Rotavirus Vaccination in Japan: A Simulation and Modelling Analysis

Introduction

Rotarix™, GSK’s live attenuated rotavirus vaccine, was introduced in Japan in 2011. A recent trend in reduction of rotavirus gastroenteritis (RVGE) due to this vaccine was described. However, an observed/expected analysis showed a temporal association with intussusception within 7 days post dose 1.

Objective

In this paper, we compare the benefit and risk of vaccination side-by-side in a benefit–risk analysis.

Methods

The number of vaccine-preventable RVGE-associated hospitalizations and deaths (benefit) and intussusception-associated hospitalizations and deaths (risk) following two doses of Rotarix™ in Japan was compared using simulations. Source data included peer-reviewed clinical and epidemiological publications, Japanese governmental statistics (Statistics Bureau, Ministry of Internal Affairs and Communications), and market survey data.

Results

For a birth cohort of 1 million vaccinated Japanese children followed for 5 years, the benefit–risk analysis suggested that the vaccine would prevent ~17,900 hospitalizations and ~6.3 deaths associated with RVGE. At the same time, vaccination would be associated with about ~50 intussusception hospitalizations and ~0.017 intussusception deaths. Therefore, for every intussusception hospitalization caused by vaccination and for one intussusception-associated death, 350 (95 % CI 69–2510) RVGE-associated hospitalizations and 366 (95 % CI 59–3271) RVGE-associated deaths are prevented, respectively, by vaccination.

Conclusions

The benefit–risk balance for Rotarix™ is favorable in Japan. From a public health perspective, the benefits in terms of prevented RVGE hospitalizations and deaths for the vaccinated population far exceed the estimated risks due to intussusception.

Electronic supplementary material

The online version of this article (doi:10.1007/s40264-015-0376-7) contains supplementary material, which is available to authorized users.

Post-marketing monitoring of intussusception after rotavirus vaccination in Japan

Purpose

Rotarix^TM was launched in November 2011 in Japan to prevent rotavirus gastroenteritis. Some studies suggest that Rotarix^TM may have a temporal association with a risk of intussusception (IS). We assessed a possible association between IS and Rotarix^TM vaccination in Japan.

Methods

All IS cases spontaneously reported post‐vaccination (Brighton collaboration levels 1, 2, and 3) were extracted from the GlaxoSmithKline spontaneous report database on the 11th of January 2013. Expected numbers of IS cases were estimated using the number of vaccine doses distributed and the Japanese incidence rate of IS stratified by month of age. The observed versus expected analysis considered the IS cases for each risk period (7 and 30 days post‐vaccination) and for each vaccine dose (two doses).

Results

Before January 2013, approximately 601 000 Rotarix^TM doses were distributed in Japan. For a risk period of 7 days post‐dose 1 and post‐dose 2, 10 and five IS cases were observed, whereas 3.4 and 7.6 were expected, providing an observed‐to‐expected ratio of 2.96 (95% confidence interval [CI]: 1.42; 5.45) and 0.66 (95% CI: 0.21; 1.53), respectively. For a risk period of 30 days post‐dose 1 and post‐dose 2, 14 and eight cases were observed, whereas 14.5 and 32.7 were expected, providing an observed‐to‐expected ratio of 0.97 (95% CI: 0.53; 1.62) and 0.24 (95% CI: 0.11; 0.48), respectively.

Conclusion

A statistically significant excess of IS cases was observed within 7 days post‐dose 1, but not post‐dose 2. These results are consistent with previous observations in large post‐marketing safety studies in other world regions. © 2015 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons, Ltd.

Validation of diagnostic codes for intussusception and quantification of childhood intussusception incidence in Ontario, Canada: a population-based study

OBJECTIVES

To validate an algorithm to identify cases of intussusception using the health administrative data of Ontario, Canada, and to apply the algorithm to estimate provincial incidence of intussusception, preceding the introduction of the universal rotavirus vaccination program.

STUDY DESIGN

We determined the accuracy of various combinations of diagnostic, procedural, and billing codes using the chart-abstracted diagnoses of patients of the Children's Hospital of Eastern Ontario as the reference standard. We selected an algorithm that maximized positive predictive value while maintaining a high sensitivity and used it to ascertain annual incidence of intussusception for fiscal years 1995-2010. We explored temporal trends in incidence using Poisson regression.

RESULTS

The selected algorithm included only the International Classification of Diseases (ICD)-9 or ICD-10 code for intussusception in the hospitalization database and was sensitive (89.3%) and highly specific (>99.9%). The positive predictive value of the ICD code was 72.4%, and the negative predictive value was >99.9%. We observed the highest mean incidence (34 per 100000) in male children <1 year of age. Temporal trends in incidence varied by age group. There was a significant mean decrease in incidence of 4% per year in infants (<1 year) until 2004 and rates stabilized thereafter.

CONCLUSIONS

We have demonstrated that intussusception can be accurately identified within health administrative data using validated algorithms. We have described changes in temporal trends in intussusception incidence in Ontario and established a baseline to allow ongoing monitoring as part of vaccine safety surveillance.

A High Incidence of Intussusception Revealed by a Retrospective Hospital-Based Study in Nha Trang, Vietnam between 2009 and 2011

Rotavirus is a leading cause of severe diarrhea among children worldwide. Thus, the World Health Organization recommended including rotavirus vaccines in national immunization programs. One concern about rotavirus vaccine, however, is a possible association with intussusception. Thus, it is crucial to know the baseline incidence of intussusception in the first year of life. A study conducted in Hanoi, Vietnam showed that the incidence of intussusception was the highest in the world. This retrospective cross-sectional study was undertaken to determine the incidence of intussusception among children <5 years of age in Nha Trang, Vietnam. Hospital charts between 2009 and 2011 were reviewed in Khanh Hoa Provincial General Hospital where virtually all cases of intussusception occurring in the city were assumed to have been encountered. The incidence of intussusception among children <1 year of age was 296 per 100,000 person-years (95% confidence interval [CI]: 225–382), and that among children <5 years of age was 196 per 100,000 person-years (95% CI: 169–226), confirming the high incidence of intussusception in Vietnam. Nevertheless, there was no intussusception in the first three months of life. We therefore recommend that the first dose of any rotavirus vaccine be administered to infants between 6 and 12 weeks of age.

Childhood intussusception: a literature review

Background

Postlicensure data has identified a causal link between rotavirus vaccines and intussusception in some settings. As rotavirus vaccines are introduced globally, monitoring intussusception will be crucial for ensuring safety of the vaccine programs.

Methods

To obtain updated information on background rates and clinical management of intussusception, we reviewed studies of intussusception in children <18 years of age published since 2002. We assessed the incidence of intussusception by month of life among children <1 year of age, seasonality, method of diagnosis, treatment, and case-fatality.

Findings

We identified 82 studies from North America, Asia, Europe, Oceania, Africa, Eastern Mediterranean, and Central & South America that reported a total of 44,454 intussusception events. The mean incidence of intussusception was 74 per 100,000 (range: 9–328) among children <1 year of age, with peak incidence among infants 5–7 months of age. No seasonal patterns were observed. A radiographic modality was used to diagnose intussusception in over 95% of the cases in all regions except Africa where clinical findings or surgery were used in 65% of the cases. Surgical rates were substantially higher in Africa (77%) and Central and South America (86%) compared to other regions (13–29%). Case-fatality also was higher in Africa (9%) compared to other regions (<1%). The primary limitation of this review relates to the heterogeneity in intussusception surveillance across different regions.

Conclusion

This review of the intussusception literature from the past decade provides pertinent information that should facilitate implementation of intussusception surveillance for monitoring the postlicensure safety of rotavirus vaccines.

Retrospective hospital based surveillance of intussusception in children in a sentinel paediatric hospital: benefits and pitfalls for use in post-marketing surveillance of rotavirus vaccines

Evaluation of the safety of rotavirus vaccines, particularly with respect to the risk of intussusception, is recommended for countries planning to introduce rotavirus vaccines into the National Immunisation Program. However, as prospective studies are costly, require time to conduct and may be difficult to perform in some settings, retrospective hospital based surveillance at sentinel sites has been suggested as an option for surveillance for intussusception following introduction of rotavirus vaccines.

OBJECTIVE

To assess the value of retrospective hospital based surveillance to describe clinical and epidemiological features of intussusception in children aged <24 months and to investigate any temporal association between receipt of a rotavirus vaccine and intussusception.

METHODS

A retrospective chart review of all patients diagnosed with intussusception at Royal Children's Hospital, Melbourne, Australia over an 8-year period including before and after rotavirus vaccine introduction into the National Immunisation Program, was conducted using patients identified by a medical record database (ICD-10-CM 56.1). Patient profile, clinical presentation, treatment and outcome were analysed along with records of immunisation status obtained using the Australian Childhood Immunisation Register.

RESULTS

A 9% misclassification rate of discharge diagnosis of intussusception was identified on critical chart review. The incidence rate of intussusception at the Royal Children's Hospital over the study period was 1.91 per 10,000 infants <24 months (95% CI 1.65-2.20). Intestinal resection was required in 6.5% of infants (95% CI 3.6%, 11.0%). Intussusception occurred within 30 days after vaccination in 2 of 27 patients who had received at least 1 dose of a rotavirus vaccine.

CONCLUSIONS

Valuable data on the incidence, clinical presentation and treatment outcomes of intussusception can be obtained from data retrieved from hospital medical records in a sentinel paediatric hospital using standardised methodology. However, there are methodological limitations and the quality of the data is highly dependent on the accuracy and completeness of the patient information recorded, the system of coding and record retrieval.

Intussusception among Japanese children: an epidemiologic study using an administrative database

Background

The epidemiology of intussusception, including its incidence, can vary between different countries. The aim of this study was to describe the epidemiology of childhood intussusception in Japan using data from a nationwide inpatient database.

Methods

We screened the database for eligible cases ≤ 18 years of age, who were coded with a discharge diagnosis of intussusception (International Classification of Diseases, 10th revision: K-561) between July to December in 2007 and 2008. We then selected cases according to Level 1 of the diagnostic certainty criteria developed by the Brighton Collaboration Intussusception Working Group. We examined the demographics, management, and outcomes of cases, and estimated the incidence of intussusception.

Results

We identified 2,427 cases of intussusception. There were an estimated 2,000 cases of infantile intussusception annually in Japan, an incidence of 180-190 cases per 100,000 infants. The median age at diagnosis was 17 months, and two-thirds of the patients were male. Treatment with an enema was successful in 93.0% of cases (2255/2427). The remainder required surgery. Secondary cases accounted for 3.1% (76/2427). Median length of hospital stay was 3 days. Of the 2,427 cases, we found 2 fatal cases associated with intussusception.

Conclusions

This is currently the largest survey of childhood intussusception in Asia using a standardized case definition. Our results provide an estimate of the baseline risk of intussusception in Japan, and it is higher than the risk observed in other countries.

Rotarix in Japan: Expectations and Concerns

A live-attenuated, orally-administered, monovalent, human rotavirus vaccine, Rotarix® (GlaxoSmithKline Biologicals, Rixensart, Belgium), was licensed and launched in 2011 as the first rotavirus vaccine in Japan. The rotavirus causes a substantial disease burden with an estimated 790,000 outpatient visits, 27,000–78,000 hospitalizations, and approximately 10 deaths each year in Japan. Since a recent clinical trial showed that Rotarix was as efficacious in Japan as in other industrialized countries, it is expected that the annual number of rotavirus hospitalizations will be reduced to between 1000–3000, and that outpatient visits will be reduced to 200,000. The universal rotavirus immunization program with Rotarix was calculated to be at the threshold of being cost-effective, even from the healthcare perspective, and it was highly cost-effective from the societal perspective, assuming that Rotarix is co-administered with other childhood vaccines. While Rotarix contains only a single G1P[8] human rotavirus, the postlicensure studies in Brazil showed that Rotarix provided a 75%–85% protective efficacy against severe dehydrating diarrhea or hospitalizations due to fully-heterotypic G2P[4] strains. While postlicensure studies detected a small and finite risk of intussusception associated with the administration of Rotarix, the authors conclude that Rotarix is safe to administer to infants between 6-12 weeks of age for the first dose and by 24 weeks of age for the second dose. However, the authors strongly discourage the delayed administration of the first dose between 13-20 weeks of age, which is allowed without any warning. Given the high incidence of naturally-occurring intussusception in Japan (185 cases per 100,000 children/year among children less than 1 year of age), this should prevent pediatricians and parents from having ill-perceptions of Rotarix being associated with an increased number of temporally-associated intussusception, and fully appreciate the benefit of the rotavirus vaccine.

Retrospective surveillance for intussusception in children aged less than five years in a South Indian tertiary-care hospital

To facilitate the assessment of the safety profile of rotavirus vaccines effectively, baseline data on intussusception are important for comparison with intussusception rates following the introduction of vaccine. The aim of the study was to describe epidemiological and clinical features of intussusception in children aged less than five years in an Indian medical facility. Hospital data on intussusception for children discharged during 1 January 2001-30 June 2004 from the Christian Medical College Hospital, Vellore, India, were reviewed. Relevant information was extracted from medical records to classify cases according to the criteria of the Brighton Collaboration Intussusception Working Group. Complete review of medical records for clinical and demographic information was only performed for those cases fulfilling level 1 diagnostic certainty (definite intussusception) (Study ID 101245). During the surveillance period, 31 infants and children with definite intussusception were identified. The majority (61.2%) of the cases occurred in the first year of life. The male : female ratio was 3.4 : 1. Intussusception cases occurred round the year with no distinct seasonality. No intussusception-associated death was recorded. This study provides baseline data on intussusception in South India. Cases identified in the study were similar in presentation and demographics as those observed in other Asian settings. Prospective surveillance systems, using standardized case definitions will further increase the understanding of the aetiology and epidemiology of intussusception, especially as new rotavirus vaccines are made available.

Population-based incidence and burden of childhood intussusception in Jeonbuk Province, South Korea

OBJECTIVES

The aim of this study was to describe the clinical characteristics of childhood intussusception and to estimate the incidence rate of intussusception before the introduction of rotavirus vaccines in Korea.

METHODS

Demographic, clinical, diagnostic, treatment, and outcome data for patients aged <5 years who were diagnosed with intussusception in Jeonbuk Province, South Korea from January 2000 through December 2002, were retrospectively collected using a standardized data collection instrument.

RESULTS

During the 3-year period, 408 patients were diagnosed with intussusception; 82.8% of children were aged <24 months. Predominant signs and symptoms were vomiting (64.5%), bloody stool (43.9%), and abdominal pain/irritability (41.9%). The combination of ultrasound and barium or air enema was the most frequently used diagnostic approach (38.7%). Three hundred and thirteen patients (76.7%) were treated by radiologic reduction, 88 (21.6%) patients were treated by surgical intervention, and the remaining seven patients had no treatment. The mean annual incidence rate of intussusception in Jeonbuk Province was 236/100,000 among children aged <2 years and 106/100,000 among children aged <5 years.

CONCLUSIONS

This retrospective study provides a background incidence rate of childhood intussusception in Korean children before the introduction of the rotavirus vaccine.

Rotavirus vaccines: entering a new stage of deployment

PURPOSE OF REVIEW

Rotavirus is the single most important cause of severe diarrhoea in infants and young children. This review provides updated information concerning three rotavirus vaccines that are being evaluated and introduced globally.

RECENT FINDINGS

Two large, phase III clinical trials, each involving more than 60,000 infants in both developing and developed countries, demonstrated that both RotaTeq (Merck & Co., Whitehouse Station, New Jersey, USA), the pentavalent human-bovine reassortant vaccine, and Rotarix (GlaxoSmithKine Biologicals, Rixensart, Belgium), the monovalent live-attenuated human rotavirus vaccine, are safe with respect to intussusception when the first dose is administered between 6 and 12 weeks of age, and that both vaccines are 90-95% efficacious in preventing severe rotavirus gastroenteritis including hospitalization. The bovine (UK)-human rotavirus reassortant tetravalent (BRV-TV) vaccine, developed at the National Institutes of Health (USA), was licensed for local production in several developing countries.

SUMMARY

Rotavirus vaccines are entering a new stage of deployment toward the goal of reducing morbidity and mortality attributed to rotavirus infection in developing countries, and hospitalizations and emergency visits caused by rotavirus in developed countries. High vaccine prices appear to offset cost savings, and may make policymakers even in wealthy countries hesitate to introduce a rotavirus vaccine into their childhood immunization programmes.

Rotavirus infection enhances lipopolysaccharide-induced intussusception in a mouse model

Unexpected reports of intussusception after vaccination with the live tetravalent rotavirus vaccine RotaShield resulted in voluntary withdrawal of the vaccine. Intussusception, a condition in which the intestine acutely invaginates upon itself, is the most common cause of intestinal obstruction in children. We report here the development of a mouse model to study rotavirus-induced intussusception. In this model, both homologous murine and heterologous simian rotavirus strains significantly enhanced the rate of lipopolysaccharide (LPS)-induced intussusception, and this enhancement was replication dependent, requiring rotavirus doses of greater than one 50% infectious dose. Rotavirus-induced intussusceptions did not have observable lymphoid lead points, despite the induction of intestinal lymphoid hyperplasia after rotavirus infection. Intussusceptions are also postulated to result from altered intestinal motility, but rotavirus infection had no effect on gastrointestinal transit. LPS-induced intussusception is associated with the induction of inflammatory mediators, and intussusception rates can be modified by inflammatory antagonists. We show that rotavirus infection significantly enhanced serum tumor necrosis factor alpha and gamma interferon cytokine levels after LPS treatment compared to uninfected mice. Together, these data suggest that rotavirus infection sensitized mice to the inflammatory effects of subsequent LPS treatment to enhance intussusception rates.